Why is the chemiosmotic hypothesis an important concept in our understanding of cellular metabolism?

A)It explains how ATP is synthesized by a proton motive force.
B)It explains how electron transport can fuel substrate-level phosphorylation.
C)It explains the sequence of the electron transport chain molecules.
D)It explains the reduction of oxygen to water in the final steps of oxidative metabolism.
E)It explains how cells can produce ATP in the absence of oxygen.